Call Dispose()()()() when you are finished using the ObserverBase<(Of <(<'TEntity>)>)>. The Dispose()()()() method leaves the ObserverBase<(Of <(<'TEntity>)>)> in an unusable state. After calling Dispose()()()(), you must release all references to the ObserverBase<(Of <(<'TEntity>)>)> so the garbage collector can reclaim the memory that the ObserverBase<(Of <(<'TEntity>)>)> was occupying.